The Break Down of a '69 Pontiac OHC inline six

Some updates for those interested enough to follow along.

Over the last week or so I've been playing with JB Weld on the head. After finding out an oil drain back passage intercepted the head bolt boss my external oil mod was made in I needed to do something about it. After thinking of a variety of ideas to work around the problem, I took the sledge hammer approach and back filled the whole passage with JB Weld then drilled out the head bolt hole. It'll do for this project, the good head will have the external line tapped elsewhere.


From the top.



From the bottom.



Then I started looking at the injector placement using the northstar injector caps. This is how I think the injector placement can go.



Using MSpaint, the Green line is the fuel In and the Yellow line is the fuel Return. I'll likely use a steel U shaped tube under thermostat housing to make the bend tighter.



So here is a completed injector assembly I'll be using. An injector bung, injector, northstar injector cap and electrical plug.



For this experiment I trimmed the bung down to the end of the injector.



I also installed freeze plugs into the engine and head. The parts store got me the steel ones instead of brass (they didn't ask and I didn't think to specify...), and I was tempted to send them back, but this engine should only be in the car around a year, so I decided they'll be good enough. The good engine will get brass ones.

---------- Post added at 09:58 AM ---------- Previous post was at 09:55 AM ----------

I thought about posting this part in the "High Tech for Old Iron" section since the DIY approach will work easily on cast iron Buick intakes as well. Actually my original plan was to 'practice' on an iron 455 intake, but it seems I don't have one on the shelf..... So I went all in on a not quite rare, but not quite easy to find 4bbl intake manifold on the OHC six. Same methods would apply to drilling a Buick intake. I have an aluminum Edelbrock one on the shelf I will eventually drill for EFI and install on the Centurion.

Oh boy, I'm committed now!!



I'll let the pictures show what I've done.

First bank has the thermostat housing adding complication.


I think I can slip the fuel line from injector two under the thermostat housing.


Next up the Q-jet/carb/throttle body is the next complication.


The electrical plug on #4 injector has to be turned around because it won't clear the cam housing.


And the easiest pair at the rear. Actually I'll be using the fuel pressure regulator cap on this end.


This one will lay out a bit different when finalized because the fuel pressure regulator.



The intake now. I still have to clean it up and then epoxy the bungs in place. #4 currently sits loose in it's hole so on mock up it's not as angled as it will end up being.



No fancy equipment here. First I drilled a pilot hole vertically, then using the same bit leaned on it a bit to give it an angle.


Then I took a standard step drill bit that to open it up to 3/4". Actually I used two different bits because I have one that goes up to 3/4" that I've cut in half so it's shorter and won't hit the bottom of the port. This picture shows where I stopped with the regular bit before I cleaned it up with the cut bit, which of course when finished looks like the hole on the left.

 

Started on proto-typing a cam sensor for the engine. I cut down the top of the distributor shaft and using some of the plexi-glass I rough cut a cap on top of it.

How it looks. I could probably paint the cap black or something and put a Pontiac arrowhead logo on it.


I gutted the mechanical advance stuff, and with the height of the walls I think I can get a relatively cheap and modern cam sensor mounted on the side of the distributor and on the advance plate I can weld on a metal tab for the sensor to pick up.


A sensor like one of these:




Might even look at speed sensors.

 

You know I am interested.... looks good

 

Amazing work!!!! What computer are you planning to use? Megasquirt?

 

Definitely MegaSquirt 3. I have the kit already and I need to start soldering it together. This will be my third one.


If this cam sensor thing works out I might modify a Buick points distributor similarly on the Skylark for a cam sensor instead of a GN sensor due to ease of access of replacement sensors.

 

Last night I finished up the MS3 assembly. Three nights while watching movies or tv.



Here it is with it's clothes missing.



I've finished up two of the intake ports on the injector bungs. I got greedy and tried to do the second set of ports and the JB weld wasn't cured and half way through grinding on one of the bungs it broke loose. So I have to redo the rear two ports and I left the front two alone as I just installed them today. The left one I ground down and the right is unfinished.



With the injectors installed.





And then I made things pretty. Still haven't installed any gaskets so it'll all have to come apart for final assembly.


I still need to paint the water pump pulley and the trigger wheel needs some drilling to mount it to the harmonic balancer.



Cleaned up the coils and painted the coil brackets.



Guess I've settled on the paint scheme, lol.



Painted the exhaust manifold as well.



A reminder of what the dual exhaust looks like. Two 2" outlets.







So the final question is, what color do I paint the intake manifold? Pontiac Blue? Red? Aluminum/Silver?

 

Great work! Alum color!

 

I haven't updated this in a while... Here are a couple update photos.

Finished up the intake and painted it. First I went with Red (too much Buick preference, lol) but hated the look on the engine so went to Pontiac Metallic Blue.




Kind of getting the feel of how the engine will look.


Took an old Q-jet that was in pieces (might even be mixed matched pieces) and gutted it for a throttle body. I actually may look at picking up an electric Q-jet for the TPS and give it the same treatment. Does 250 cubic inches need this much air? Eh, why not.




I finally put some gaskets in the engine, so now it's together for the long haul. Also bought coil wires.


Installed an internally regulated alternator on it as well.




Had to knock out the warm-up back pressure valve, which left two holes in manifold. A quick taping of the holes, some JB weld on bolt threads and a bit of grinding and it's good to go.


I installed version 1.0 of the injector fuel lines. I'm not entirely happy with the fuel line loop, but any tighter and it'll kink.





So I'm looking at digging up this old design thought with the injector pair rail, but might modify the design by running short lengths of rubber EFI hose between the rails instead of steel.




I'm going to the junkyard this weekend and I am going to be looking for a sensor suitable to use as a cam sensor on this engine. That might be an actual cam sensor or it might be a speed sensor. Also I need to fabricate up a crank trigger mount. There are a couple of convienient bolt holes on the side of the block under the alternator that I should be able to make use of.

 

Will the Chevy lump inserts work on this head? The ports look VERY similar to the Chevy 250 and would be a fairly cheap and easy (relatively) to increase the flow characteristics for the intake. I'm an old inliner from way back so I love this project.
http://12bolt.com/lump_head_information/installation_instructions

 

No, the lumps I believe would actually hurt the performance of this engine. One of the big upgrades to the Chevy inline six is the lump port because two cylinders share one intake port, and an upgrade from that is to a true 12 port (six intake, six exhaust). The Pontiac engine came from the factory nearly a perfect 12 port. There is a little ~1/8" gap right at the manifold flange, and on my good head that has been welded up and re-surfaced to be a true 12 port.

Stock head:


My good head waiting for porting and valve work:


Since I'm posting here, a minor update.

Made up two fuel rail pairs the other day to replace the injector caps. I need to make a third one for the middle pair, but I need to break out the injector bungs and re-JB Weld them in as I staggered them a bit one above the other for the injector caps. I'll probably start by trying to link the pairs with steel tubing. I'll have to cut the tubing and re-double flare it. If I find that problematic I'll get barbed nipples and use some braided EFI line I have between the pairs.








I'm also abandoning my T5 plan, as much as I'd like to row the gears behind this six. I'm going to make a go at rebuilding the 2004r I have as soon as I have the Skylark back on the road.

 

Good call going with an auto trans!

If you are like me then you would like to manual shift the auto and have the best of both worlds... Control over the shift points and no clutch or lost time shifting. I am using an electronically manaul shifted 4L80E and I think it will work well.

 

I figured I'd be able to get the 5-speed up and running quicker, and only behind the naturally aspirated engine, as the turbo engine would definitely get the automatic. Now I figure I'll rebuild the 2004r myself that was in my Skylark for the better part of a decade (behind the old 231 V6) and go that route.

Eventually I might go with a 4L60e or 4L65e to do away with the TV cable altogether (megaShift), but that decision will be down the road. I will have the lock up converter function controlled by the MegaSquirt though from the start as that will be very simple to do. I want to install a stock console with a stock automatic shifter with the gate teeth updated for the OD.

 

I am running a 4l80E with a little computer that gives me manual control using buttons on the steering wheel for up and down and I will still use the column shift to select park, drive and reverse. I only paid $300 for the computer so it is not bad... I will just run a toggle switch for the lockup.

 

Couple minor updates. Going out to do some work on it today.


A while back I picked up a chunk of drive shaft out of a local machine shops scrap yard to use as part of the induction system for the turbo engine. A little mock up, there will be tapered runners to the head. Once sanded and primered it ought to look decent. I need the engine in the car to do a proper mock up for length though.











Also yesterday I worked on making the cam sensor for the sequential EFI and coil on plug ignition by modifying the distributor some more and adding a sensor to the flat cap I made. It's actually just a prototype for now, I'll make a new plexiglass cover for the final product.


First I cut the advance plate into a tab.



Then I took the top plexiglass plate and drilled a hole in it that the sensor fits through. I contemplated going with a full grommet set up, but the sensor really needs to sit on the plexiglass to get low enough for it to pick up the tab. I used a cut down transmission dipstick tube grommet to minimize vibration. I might zip tie or black RTV it on there. Then I drilled and tapped a hole for a 1/4-20 bolt.




Then plopped it on the engine. The wiring harness is pointing towards the coolant temp sensor so the wiring harness should look relatively clean there. If the sensor doesn't reliably pick up the tab I'll either bend the tab a bit or weld a washer or strip of metal to the top of it. Hopefully this is sufficient to run as a cam sensor.

 

Got some more work done on this today. Made the center injector rail, connected it to the outer two with steel braided hose. Started on the wiring. I have all the signal wires for the ignition coils ran as well as the fuel injector wires. I need to run the power and ground wires for the coils still, but have to pick up some wire to finish it. I also ran the coolant temp sensor wires. I wanted to do the cam sensor wiring, but realized I don't know which wires do what =P So I have to sort that out. It's a stock hall effect cam sensor off a GM 4-cylinder if anyone happens to know.


Drilled out the middle injector rail. Not very sophisticated but it works (well I hope it does...)



The injectors just peaking into the line. Actually they are pulled down a bit once installed as I found the connectors wouldn't plug in until I lifted the rail some.



This is where I ended the day. The injectors are in, the rails are linked up and the wiring harness is getting fatter. Lots of the wires might look the same, but actually they have different color stripes on them as well as text labeling printed on them.



And on the ignition side of the engine.


---------- Post added at 06:29 PM ---------- Previous post was at 06:22 PM ----------

Oh, and I made a final cam sensor cap and installed the flywheel for later when I try and run the engine on the stand.

I won't win any art contests, but it looks sufficient enough for my purposes.

 

Good work!

 

Thanks Sean. I should rename this thread the "Building up of a '69 Pontiac OHC inline six" lol.

 

Started up working on this again. I didn't take any pictures of it, but I installed an OHC starter nose cone on a Buick 455 starter for a bit more oomph starting up.


Got the project work board out for this one. I've added a few things to the list since I took the picture, like add oil and prime the system.



Got the exhaust system for the run stand sorted out. I may have to cut the pipe just before the bend and adjust from there once in the car, this will do for now.
.


No where in Ely sells exhaust reducers so I had to improvise. So a few slices, some hammer taps and some welding fill. Due to my (lack) of awesome skills I had to fill a lot of gaps where the second pipe slide into that hole.



I also fabricated up the crankshaft sensor mount as well as did final mounting of the alternator, complete with new belt.



Got the sensor wiring routed safely around the exhaust. I'll put the alternator charging wire into the black loom when I wire it up.



Tomorrow's plan is to work on the fuel system and finish up the wiring.

 

This is going to be crazy......awesome work ....the t 5 trans is what I have on my Ohc motor its fun.....

 

If your interested I have a neighbor that's got a Firebird that originally came with the OHC 6, has a 400 in it now. I can get you guys together if you want. It is a project ad it needs sheet metal replaced but its a good starting point for your project